Sex Pheromone of the Rice Leaffolder Moth, Cnaphalocrocis Medinalis (Lepidoptera: Crambidae): Synthetic Indian and Philippine Blends Are Not Attractive to Male C
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Appl. Entomol. Zool. 36 (4): 471–474 (2001) Sex pheromone of the rice leaffolder moth, Cnaphalocrocis medinalis (Lepidoptera: Crambidae): Synthetic Indian and Philippine blends are not attractive to male C. medinalis, but are attractive to C. pilosa in the South-Western islands in Japan Kei Kawazu,* Osamu Setokuchi,1 Katsuyuki Kohno,2 Keiichi Takahashi,2,3 Yutaka Yoshiyasu4 and Sadahiro Tatsuki Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113–8657, Japan 1 Ohshima Branch, Kagoshima Prefectural Agricultural Experiment Station, Naze, Kagoshima 891–0068, Japan 2 Japan International Research Center for Agricultural Sciences, Okinawa Subtropical Station, Ishigaki 907–0002, Japan 4 Faculty of Agriculture, Kyoto Prefectural University, Kyoto 606–8522, Japan (Received 18 June 2001; Accepted 13 July 2001) Abstract Field bioassays with 3 different types of synthetic pheromone blends (Japanese, Indian and Philippine blends) based on geographic variation in the sex pheromones in Cnaphalocrocis medinalis were performed in 1998 and 1999 in the South-Western Islands of Japan. Only the Japanese blend attracted C. medinalis males, while neither the Indian nor the Philippine blend showed attractiveness, as in the Japan mainland. However, both the Philippine and the Indian blends attracted males of a different species, C. pilosa, which is closely related to C. medinalis. Geographic variation in the sex pheromones of C. medinalis as well as the relationship between C. medinalis and C. pilosa are discussed. Key words: Rice leaffolder, Cnaphalocrocis medinalis, Cnaphalocrocis pilosa, geographic variation, sex pheromone (Z)-11-octadecen-1-ol (Z11-18:OH) and (Z)-13- INTRODUCTION octadecen-1-ol (Z13-18:OH) at a ratio of 11 : 100 : The rice leaffolder, Cnaphalocrocis medinalis, is 24 : 36 (Japanese blend) (Kawazu et al., 2000). a migratory rice pest in several Asian countries. In Furthermore, field bioassays using the 3 syn- Japan this species fails to overwinter except in the thetic pheromone blends in various districts of the South-Western Islands and, thus, the distribution in mainland of Japan as well as at Hangzhou, China, the mainland of Japan is seasonal. The major showed that only the Japanese blend caught signifi- source of immigration has been suggested to be cant numbers of male moths, while neither the southern China, i.e. southern areas of the Yangzhe Philippine blend nor the Indian blend showed any Valley. During the annual rainy season in Japan attractive activity (Kawazu et al., submitted). These from June to July the moths may migrate to Japan findings suggest that males of most populations with the aid of low level jet streams (Wada et al., that migrate to the mainland of Japan (Kyushu and 1980; Kamiwada et al., 1994). northward) are responsive to the Japanese blend There are considerable geographical variations alone. in the sex pheromone components of C. medinalis; However, in consideration of the geographic and Indian and Philippine populations use (Z)-11-hexa- climatic conditions in the South-Western Islands of decenyl acetate (Z11-16:Ac) and (Z)-13-octade- Japan, it is also possible that moths originating cenyl acetate (Z13-18:Ac) at a ratio of 1–6 : 20 (In- from other regions such as Taiwan or the Philip- dian blend) (Ganeswara Rao et al., 1995) and 98 : 2 pines migrate to these areas (Mills et al., 1996). (Philippine blend) (Ramachandran et al., 1990), Furthermore, the migrants may colonize these is- while Japanese populations use (Z)-11-octadecenal lands where they can overwinter. It is, therefore, (Z11-18:Ald), (Z)-13-octadecenal (Z13-18:Ald), possible that immigrant moths originating from * To whom correspondence should be addressed. 3 Current affiliation: National Food Research Institute, Ibaraki, Japan 471 472 K. Kawazu et al. various regions have cohabited these areas. To test this possibility, field bioassays using 3 synthetic pheromone baits were conducted. MATERIALS AND METHODS Chemicals. Synthetic monounsaturated alde- hydes, alcohols and acetates were generous gifts of Shin-Etsu Chemical Company (Tokyo, Japan). The compounds were purified by column chroma- tography in the same manner as in a previous re- port (Kawazu et al., 2000). Gas chromatographic analyses showed that the purified compounds con- tained ,0.1% of the corresponding E-isomers (Kawazu et al., 2000). Field bioassays. Baits were prepared using the gray halo-butyl isoprene blend elastomer septa (West Co., Singapore). The required amounts and ratios of the synthetic compounds, each dissolved in 200 ml hexane were poured onto the inner sur- face of a rubber septa. After evaporation of the sol- vent, the baits were placed in aluminum laminated polyethylene bags and stored at 220°C until use. The composition and amount of the synthetic pheromone components used for each septum were as follows. Japanese blend; Z11-18:Ald (55 mg), Fig. 1. Testing sites (Amami-Oshima Is. and Ishigaki Is.). Z13-18:Ald (500 mg), Z11-18:OH (120 mg) and Z13-18:OH (180 mg); Philippine blend; Z11-16:Ac (500 mg) and Z13-18:Ac (10 mg); Indian blend; males at each site were transformed to SQRT Z11-16:Ac (50 mg) and Z13-18:Ac (500 mg). (X10.5) and differences among means were tested Bioassays were conducted in paddy fields in for significance by Tukey’s test. Amami-Oshima Is. and Ishigaki Is. in 1998 and 1999 (Fig. 1). Sticky traps (SE Traps, Sankei RESULTS Chemical Company, Tokyo, Japan) were used in Amami-Oshima Is. in 1998 and in Ishigaki Is. in In Amami-Oshima Is., only the Japanese blend 1998 and 1999. Cone traps slightly modified from showed attractiveness to C. medinalis males as on those reported by Kawasaki and Sugie (1990) were the mainland of Japan (Table 1). In contrast, the used in Amami-Oshima Is. in 1999. Results of field Philippine blend showed attractiveness to males of bioassays comparing the effectiveness of various Cnaphalocrocis pilosa, a closely related species to trap designs will be reported elsewhere. C. medinalis, while the Japanese blend did not Generally, at each test site traps containing a se- (Table 1). The Indian blend also caught a small ries of baits (the Japanese, Indian and Philippine number of males of C. pilosa, although the number blends, and control) were arranged. The distance was not significantly different from the control between traps within a block was approximately (Table 1). In Ishigaki Is., Okinawa, the Japanese 10 m and the distance between blocks was approxi- blend also caught males of C. medinalis, while the mately 100 m. When checking the numbers of Philippine and Indian blends also caught males of trapped moths, the trap locations were moved one C. pilosa, although the number was not signifi- position forward within a block. The numbers of cantly different from the control due to very low trapped moths were checked once a week. trap catches (Table 2). In statistical analyses, the numbers of trapped Sex Pheromone of Rice Leaffolder Moth 473 Table 1. Comparison of attractiveness of Japanese, Indian and Philippine blends of synthetic sex pheromones to male moths in Amami-Oshima Is., Japan Total no. of males caughta Source 1998b 1999c C. medinalis C. pilosa C. medinalis C. pilosa Japanese blend 20 a 0 a 59 b 0 a Indian blend 0 a 26 a 0 a 3 a Philippine blend 0 a 154 b 0 a 335 b Control 0 a 1 a 0 a 0 a a Values followed by the same letters within each column are not significantly different at the 5% level by Tukey’s test using SQRT (X10.5) transformed data. b Tested with two traps for each lure between April 21 and July 29, between August 11 and September 4, between October 29 and December 24. c Tested with one trap for each lure between April 9 and October 4. Table 2. Comparison of attractiveness of Japanese, Indian and Philippine blends of synthetic sex pheromones to male moths in Ishigaki Is., Japan Total no. of males caughta Source 1998b 1999c C. medinalis C. pilosa C. medinalis C. pilosa Japanese blend 2 a 1 a 2 a 0 a Indian blend 1 a 6 a 0 a 8 a Philippine blend 0 a 5 a 0 a 23 a Control 1 a 0 a 0 a 0 a a Values followed by the same letters within each column are not significantly different at the 5% level by Tukey’s test using SQRT (X10.5) transformed data. b Tested with three traps for each lure between September 2 and December 21. c Tested with three traps for each lure between April 23 and November 24. and C. pilosa, cohabit in the South-Western Is- DISCUSSION lands, they should use different pheromone compo- Cnaphalocrocis pilosa (5Marasmia latimargin- sitions. A similar situation was found in C. medi- alis) is widely distributed in the Kanto district and nalis and Marasmia (5Cnaphalocrocis) patnalis, a westward in Japan and Taiwan, Southeast Asia and close species of C. medinalis, in the Philippines India, and in Japan, the larvae of this species are (Ramachandran et al., 1990; Ganeswara Rao et al., known to feed on Japanese pampas grass, Miscan- 1995). The EAG-active components of M. patnalis thus sinensis Anderss (Yoshiyasu, 1980). Since C. were reported to be Z13-18:Ac and Z11-16:Ac at a pilosa males in the South-Western Island showed 96 : 4 ratio (Ramachandran et al., 1990), which is responsiveness to the Philippine blend and possibly very close to the pheromone blend of C. medinalis to the Indian blend of the sex pheromone of C. in India. medinalis, it is possible that the sex pheromone It is important to research the chemical commu- system of C. pilosa includes Z11-16:Ac or Z13- nication between C.